Abstract: A heat-sensitive recording material comprises a sheet substrate applied thereon with a heat-sensitive, color-developing layer containing as the main components a colorless or light-colored leuco dye, a developer for permitting said dye to develop a color by heating and a binder, in which the binder used is an ammonium salt of a diisobutylene/maleic anhydride copolymer is expressed in terms of the following general formula: ##STR1## wherein R stands for a diisobutylene group a part of said ammonium salt being substituted and modified by an ammonium salt comprising a primary, secondary or tertiary ethanol amine.

Abstract: A heat-sensitive recording material is disclosed, comprising a support having thereon a heat-sensitive, color-forming layer mainly composed of as color-forming components a colorless or pale-colored leuco dye and an acidic compound capable of allowing said leuco dye to color develop by heating, wherein said heat-sensitive, color-forming layer comprises a color former comprising a fluoran derivative represented by the following general formula (I): ##STR1## wherein R.sub.1 and R.sub.2 each represents a lower alkyl group, and X represents a halogen atom, a lower alkyl group, a cyano group, or a nitro group, a developer comprising bis(p-hydroxyphenyl)sulfone or a derivative thereof represented by the following general formula (II): ##STR2## wherein R.sub.3 and R.sub.

Abstract: A heat-sensitive recording material composed of a heat-sensitive, color-forming layer on a sheet substrate. The heat-sensitive, color-forming layer is mainly composed of a color-forming component consisting of a colorless or light-colored leucodye and an acidic compound for allowing said leucodye to develop color by heating, and further includes on the upper surface thereof a protective layer composed mainly of a polyvinyl alcohol and containing an epoxy compound having in its molecule at least two epoxy groups or an ethylenimine compound having in its molecule at least two ethylenimine groups.